This is an automatic advance unit as applied to the circuit breaker ignition of motorcycles, notably such as are utilized in the Harley-Davidson ignition system dated from the year 1970 to the present. The objective herein is to permit motorcycle users to obtain many additional miles of riding pleasure out of their motorcycles, without advance unit replacement, in accordance with the preferred system of the invention.
In the ignition circuit breaker advance unit of the invention, flyweight roll-pins are not set in the flyweights, per se but they are mounted in the advance unit backing plate, ensuring that the flyweights are moveable in perfect horizontal position, whereas in the prior art device, the flyweights on the advance unit set the roll-pins in the flyweights, per se, causing severe wear when centrifugal spinning of the advance unit is occurring. Thus in the instance of the prior art, the generated centrifugal force causes the flyweights to wear catty-cornered, which will allow them to rub against the timing plate, wearing them out in a shorter period of time than in the present ignition control system. The bottom of the flyweights of this invention ride in contiguous contact with the timing plate, a lubricant providing the only intermediate for surface to surface contact.
The centrifugally activated flyweights of this invention are mounted in such a manner that they may perform for a life of well over 5,000 miles without replacement. There is, to accomplish the present objective, a breaker cam with substantially shorter flyweight engaging slots and thus less tolerance between elements, reducing wear as opposed to existing competitive advance units. Advance units of prior art devices must be replaced at approximately every 1,000 miles because of excess flyweight wear occasioned by the design of the original issue advance unit. Other advantages of the invention include maintaining the compression springs holding the flyweights together as a unit, to function with the baseplate. Since the flyweights do not wear nearly as fast as in prior art assemblage, the invention herein yields more dependable and lengthy service. In the present system, shafts from the flyweights engage holes on the advance assembly baseplate per se, ant the breaker cam herein is of a unique dimension, as is the advance assembly shift. Likewise, the cut-out slot in the breaker cam herein is shorter, presenting less operative tolerance, therefore sustaining less wear than occurs in existing units.